Solenoid coil across Hall effect sensor

[mutthunaveen]

Dear Board

i have a coil based hall sensor which will measure currents from 100mA to 600A. this is placed just beside a HV switching coil (12V 1A coil).
this coil will on off the power from a power source and the hall sensor measures HV current flowing towards load.

Im worried if hall sensor placed just 2 cm away from solenoid??

is there any impact i need to study and consider or is it safe??

Thank you
Naveen

 

[KlausST]

Hi,

I´d say it is very likely that the hall sensor is influenced by the magnetic field of the coil.
...as long as the coil is not magnetically shielded

Klaus

 

[mutthunaveen]

Hmm..

thanks, i think coil is not shielded... and is there any way i can make hall effect sensor work in noisy invironments without any error in current measurement??

or is hall sensor shielding possible??

how can i get out of it?? any suggestion.

 

[KlausST]

Hi,

If the coil current is DC and your measurement current is AC only, then put a HPF in the hall sensor signal path.

Maybe a magnetic core in combination with the hall sensor could amplifiy measurement signal, and the same time suppress coil signal.

But without knowing your application details.. it´s just guessing.

Klaus

 

[mtwieg]

Do you have a rough idea of what field strength to expect from the coil at the hall sensor's location? Ideally it should be using close to the full scale range of the sensor, in order to maximize SNR.

Without a more detailed description it's hard to give recommendations on shielding.

 

[mutthunaveen]

Hello.

My Application is DC solenoid coil isolating batttery -ve terminal from charging circuit.
im disconnecting battery after charging or after some operation using a solenoid valve.

im worried if the hall sensor pics up solenoid continious flux when solenioud coil is engaged. solenoid coil draws upto 1.2 Amps which is little high continiously to hold the contactor.

i have placed this solenoid 2 CM away from battery (as nearest as possible) and current sensor (hall sensor) 2CM away from solenoid. (battery +ve terminal <--> disconnect contactor <--> hall sensor).

i hope this is clear.

will hall sensor pick up solenoid coil energised flux and give me wrong reading instead of measuring correct value from + ve battery terminal current?

thank you.

 

[KlausST]

Hi,

So both are DC currents.
May I ask why you need to mount them in close proximity? The relay will do the same job at any place between charger and battery, it can be placed in positive or negative wire...and the same is true for the hall sensor.

You may use a Mosfet instead of the relay.
You may use a shunt instead of a hall sensor.
You may use ready to buy current sensors with ferrite core.

Many ways to avoid the problem....

Klaus

 

[mutthunaveen]

thanks for options..

this is HV battery around 100V (few cells in series) and solenoid coils operate in 12V ...
and both + and - terminals solenoid contactors are placed. i have placed them very near due to packaging constraints. to make the package small..

i cannot go with shunt due to some reasons.
i cannot go with MOSFET because the current is bit heavy and they are not good for SC.. they fail so fast.

if i buy current sensors with ferrite core then issue is solved?? no need to worry about any other solenoid feilds or near magnets??

 

[KlausST]

Hi,

You give only vague informations.
* I have no idea what "the current is so heavy" means.
* I don´t know what "a small package" is for you.
* 100V is not related to magnetics... current is more informative.
* I don´t know waht you mean with "some reasons"
Values could give much more information.

"They fail so fast" ... is only true if you don´t keep on datashhet specifications.

Sensor with ferrite core:
As said in post#2: "Maybe a magnetic core in combination with the hall sensor could amplifiy measurement signal, and the same time suppress coil signal. "

Without specifications... hard to give better assistance.

Klaus

 

[mutthunaveen]

Hmm..

battery is 100V and rated current is 100Ah. and i need to design this in as small package as i can. (so i need to keep almost all components closer).
the solenoid to isolate battery operates with 12V and it consumes 1.5A. This 12V and 1.5A should in solenoid coil will create some flux to pull the plunger.

will this effect hall sensor which is 2cm away from the contactor..
magnetic core wtih combunation with hall sensor could be the better choice.

let me see.

 

[mtwieg]

I see, you are measuring load current with the hall sensor and want to avoid the solenoid field interfering with it. The answer depends on the geometry of the solenoid coil, the geometry of the hall sensor, and their relative orientation. Can you share their model numbers?